The III-V group compounds are widely applied in the photoelectric devices due to the advantages, such as good stability, low effective mass, high electron mobility and peak velocity, high light absorption coefficient, etc. Among these, the band gaps of the InxGa1-xAs (0≦x≦1) materials can vary in the range of 0.35 eV (InAs)˜1.43 eV (GaAs) with the changes of the In components. According to these characteristics, the InxGa1-xAs materials, particularly the In0.53Ga0.47As material with the in component of 0.53, can be applied in the room temperature infrared detectors and the highly efficient tandem solar cells.
InP, GaAs and Si are commonly used as the substrate for epitaxially growing the In0.53Ga0.47As material. But InP and GaAs are expensive, small in wafer size, and brittle, which are not beneficial to the industrial production. As compared with the InP or GaAs substrate, the Si substrate is inexpensive, and easy to operate in large size. At the same time, most of the integrated chips on the present market are Si-based, therefore growing an In0.53Ga0.47As film on Si facilitates integrating the same into the existing chips. However, as there are large lattice mismatches (≈9%) between the Si and the In0.53Ga0.47As material, if In0.53Ga0.47As is directly grown on the Si, a large amount of residual stress will occur in the obtained film. And large residual stress will have a great effect on the properties of the In0.53Ga0.47As film. On one hand, large residual stress may cause crackles or even cracks on the In0.53Ga0.47As film during its growth. On the other hand, large residual stress will cause a large amount of defects in the In0.53Ga0.47As film, thus deteriorating the device performance. In order to grow an In0.53Ga0.47As material with a high quality on the Si substrate, the best way is that first a buffer layer material is epitaxially grown on the Si substrate to release the stress, then the In0.53Ga0.47As material is epitaxially grown. But in the growth of In0.53Ga0.47As at present, the most used are the multilayer buffer layer structures with graded buffer layer, step-graded buffer layer, invert-graded buffer layer, and the like, which often result in that it is necessary to epitaxially grow the multiple thick buffer layers before growing the In0.53Ga0.47As material, and the growth steps are complicated and it is difficult to precisely control the constituent, thickness, and crystal quality of each layer of the materials, thus affecting the quality of the finally obtained In0.53Ga0.47As film. Therefore, in order to obtain an In0.53Ga0.47As film with low residual stress and high quality, it is required to optimize the growth process of the buffer layer.